Chemical Elements

Everything is made out of chemical elements. Water, food, stones, even you. They are substances, that can’t be further divided by ordinary chemical processes. At present there are 118 known elements, of which 20% can’t be found in nature and are known just because they have been produced synthetically in the laboratory. Under ordinary conditions, 11 of these 118 substances are gases, 2 are liquids and the rest are solids. The elements can combine into compounds. The theoretical number of the compounds is almost infinite. To date, 1 million compounds are known and more are discovered every day. If two or more elements combine into a compound, they may lose some of their old characteristics. There are also chemical mixtures, but it is able to separate the components with the help of physical processes, while compounds can’t be separeated by physical processes, but by chemical processes. E.g. coffee with milk is a mixture, while oxidated iron is a compound.

Atoms

Each element is actually an atom. All atoms differ from each other. They have different numbers of protons, electrons and different weight, but they all have the same neutral electrical charge. The neutral charge is caused by the fact that atoms usually have the same amount of electrons (they are negatively charged) and protons (they are positively charged). There is also a third part, the neutron, which has a neutral electrical charge and only influences the weight of the atoms. The neutrons and protons form together the nucleus of the atom. The nucleus is surrounded by a “cloud” of electrons, circling around it. The number of protons is equivalent to the atomic number.

Neutrons and protons have similar weights, and they usually define the weight of each atom. Electrons are so light, that they don’t influence the weight of the atom. The number of neutrons can vary, but the element remains the same, just the weight changes. An example would be hydrogen. Hydrogen atoms ususally have just one proton and no neutrons, but if they have a neutron, they still are hydrogen atoms, but they have different weights. These are called isotopes. Each atom has a mass number, which is equivalent to the average of the numbers of neutrons and protons in the nucleus each isotope of the atom has.

There are also ions, which are basically substances that differ from the atoms only with the number of electrons. An ion with more electrons than protons would be an anion (-) while the cation has more protons than electrons (+).